Invertebrates fed on live phytoplankton will have a higher natural HUFA content and increase their nutritional value to fry. Nannochloropsis and Tetraselmis have traditionally been used for rotifer and Isochrysis and Pavlova have also proved effective to rear copepod cultures.

To maintain and develop your phyto culture you need to set aside an area with a warm stable temperature, aeration for the culture vessels, 1-2 plant bulbs rigged approx. 200mm to the side of the culture vessels, and a timer providing 12-24 hours of light per day. Aim to set up 4-6 separate cultures in case a culture crashes.

If you are new to culturing phytoplankton set up your culture undiluted, add 1ml fertiliser per 2.5 litres of culture, and leave for the first week to ensure it settles in.

Once the phytoplankton is stable your first new culture can be set up with 1 part mature culture and 1 part new culture water. Add the fertiliser at a rate of 1-2ml per 2.5 litre of culture. Traditionally, ratios of 1 part mature culture and 3 parts new culture water have been successful but with this greater dilution effect you are at greater risk of a culture crash. Be realistic on the volumes of phytoplankton you need and balance this with the rates of dilution used, and the number of cultures you wish to set up.

For further reading look no further than the Plankton Culture Manual.

For a culture 'reactor' go to a major supermarket and buy the 5 litre mineral water bottles at 80-90 pence ea., drill the lid, add a rigid plastic airtube and you're away.

Starting a culture from a phyto disk

We normally have phyto disks for Nannochloropsis, Tetraselmis, and Isochrysis phytoplankton kept in stock under refridgerated conditions. The phyto disks are specially prepared for long term storage (up to 12 months) and suitable for the infrequent user or as a backup to active cultures that may have crashed or become cross contaminated.

For first 24 hrs add sterile salt water to the dish so that the algal cells are submerged and then place under constant light.

Use a sterile swab to gently rub the algal cells from the agar plate. The Iso cells will come off the dish in clumps when you use it. Start with only 500 mls of water and add fertiliser at 0.2ml per 500ml of culture.

After 1 week the culture should have matured and ready for splitting or dilution. Add fertiliser at 1ml per 2.5 litre culture

Additional Notes for Isochrysis culture:

At the initial 500ml culture stage ensure the Isochrysis clumps remain in suspension and avoid letting them stay around the top of the container - leave culture to develop for a week.

If after 1 week the culture has not developed a brown colour just add more fertiliser and leave to grow for another week.

After 2 weeks, if the culture still has not developed a brown colour transfer 300ml of the culture to a fresh vessel, add replacement 200ml fresh salt water and fertiliser. Keep the culture at a maximum of 500ml until the culture is chocolate brown in colour.